THE DESERT OF AUSTRALIA. -- CAUSE OF THE HOT WINDS. -- GEOLOGY.
I intend in this chapter* to give an explanation of the cause of the
hot-winds of Australia; to throw out a suggestion on the most likely
mode of prosecuting discovery towards the interior; and to conclude
with a slight sketch of the geology of the colony. Before doing this
I shall give a brief account of a journey made by myself and Mr.
Maxwell Lefroy in search of the inland sea so often talked of, and
which a native promised to show to us; so large, he said, that when
he stood on one shore he could not see the other. Although this sea
turned out to be a pure fiction, the journey was not entirely
useless, nor altogether uninteresting. As this sea was probably not
more than 200 miles distant from York, according to the reckoning of
the native, who said it was "ten sleeps off," I judged that one
month's provision would be sufficient.
[footnote] *This chapter I owe to Mr. Henry Landor.
Accordingly, Mr. Lefroy and myself started on the expedition, on
horseback, taking with us a native boy, and a pack-horse loaded with
flour, tea, and sugar, and other necessaries. It will be sufficient
to state that we pursued a south-east course, crossing the Hotham,
the Williams, and the Arthur rivers, and traversing an indifferent
country, but in many places fit for sheep-grazing, before we came to
the lake, or sea, of which we were in search. When we arrived at it,
we were disappointed to find it not more than six miles long,
although the natives, with their usual amount of exaggeration, had
increased it to an illimitable ocean. Before descending from the
high land to the plain in which the lakes are situated, we caught a
distant glimpse of what appeared to be a grand and broad river,
pursuing a winding course through a magnificently wooded valley, with
its clear bright waters dwindling in the distance to a silvery
thread. A nearer examination, however, dispelled the illusion, and
the beautiful river turned out to be nothing more than a chain of
shallow lakes, situated in a woody valley; and only in very wet
seasons flowing from one to another.
We determined to follow the chain of lakes eastward, so long as our
provisions should last, or as long as our horses could find food for
themselves. We proceeded east for six days, passing numberless
lakes, and observing that the chain divided, one branch of lakes
running north-east, and the other due east. We followed the latter
until we came to a lake called Dambeling, by far the largest we had
seen, being about fifteen miles long by seven or eight wide, with a
good sheep country on its northern bank, and a river, which we called
the Lefroy, falling into its eastern end. The river was about thirty
yards wide, with a clayey bed, and large fresh-water pools, and
flowed from the east, through the worst country we had seen, it being
an apparently endless desert, and level to the horizon. We went one
day's journey into this inhospitable country, but the want of food
for our horses, and our own unprepared state, prevented us from
penetrating farther. On our return, we went for two or three days
north, on the outskirts of the desert, before we turned westward on
our way back to York.
The only land we crossed in this expedition was situated on the head
of the Hotham and Williams. The area of this country is undoubtedly
very great, but its average character is below the York district,
although it is well adapted for sheep-grazing.
But the most interesting feature is the barren and desolate country
to the east of Lake Dambeling, doubtless a continuation of the same
sterile country seen by Mr. Roe, the surveyor-General, east of York
many years previously; and probably from Mr. Eyre's observation,
extending quite down to the southern coast. We had no means of
ascertaining the width of this dreary country, but we did not think
it could be impassably wide because the river Lefroy appeared to come
across it. This river, in a geographical point of view, may be
important, as the character of its bed, without trees, more
water-worn than the other rivers of the colony, its size, and the
direction from which it comes, render it exceedingly interesting to
determine how it is supplied. The sandy nature of the country on its
banks, and for many miles east, and the flatness of the country,
preclude the idea that it receives its supply of water from the
immediately surrounding district. It must either be supplied by a
country of a far better character to the eastward, or it is the
outlet of another and larger lake far in the interior. From the
natives we could learn nothing but that there were no kangaroos, no
opossums, and no water to the east; but as their knowledge never
extends 100 miles, and they would tell any lie to avoid going where
they had no inclination to go, their opinions are worthless. It
might be worth the while of the colony to send forth another
expedition to determine the boundaries of this desolate country, as
it is not improbable that a practicable rout might be discovered to
South Australia by means of the river and lakes.
The outlet of the lakes is into the river Beaufort, and possibly also
into the Gordon. There is no doubt that in exceedingly wet seasons
the whole valley is one continuous stream, when all the lakes would
be united and present a truly magnificent appearance; but as the area
of evaporation is so large, and the banks of many of the lakes are
high, the quantity of rain must be enormous before the valley becomes
filled with a running river. Lake Barbering, where the valley
divides, has a steep shore, with three distinct marks of former
water-levels. All the lakes have two or more shores, showing either
a decrease of rain or an elevation of the land itself, probably both.
Between the present and ancient shores there is a belt of swamp-oaks
and tea-trees, which show that some length of time has elapsed since
the water left its old levels.
The water to fill these large reservoirs must come down the river
Lefroy, as the neighbouring country is too sandy to supply it in
sufficient quantities.
No question in geography has presented a wider field for conjecture
than the much-debated one of the nature of the interior of Australia.
Is it desert, or water, or pasture? inhabited, or destitute alike of
animal and vegetable life? The explorations of Captain Sturt, and
the journey of Mr. Eyre, would incline us to believe that the country
is one vast sterile waste; but the journey of the latter is worth
nothing as an attempt to expose the nature of the interior, since he
never left the coast. It certainly shows how much suffering the
human frame can endure; and whilst, as illustrative of Australian
geography, it is valueless, it is highly creditable to the energies
of the traveller.
The expedition of Captain Sturt has shown that to the north of South
Australia the country is chiefly desert, totally incapable of
supporting animal life: while the geological specimens of that
traveller prove that the rich mineral strata of South Australia
extend far beyond the pastoral boundaries of the colony. A reference
to the journey of Mr. Lefroy and myself, from York to the south-east,
will show that there exists a low level country running far beyond
our farthest eastern point, which may afford abundance of water and
pasture for any future expedition proceeding in that direction.
An expedition starting from these lakes in the BEGINNING OF WINTER,
so as to take advantage of the first supplies of water, might advance
far enough into the interior to discover at least the possibility of
proceeding before the succeeding summer would render it impossible to
return; for the lakes alone would not be sufficient to ensure a
supply of good drinkable water during the summer, as they generally
become quite salt long before summer is over. It would be necessary
to find a good deep water-hole for the party to remain at during the
dry season, and from which they could push out small lateral
expeditions as a sort of foundation for the next season's main
advance. Expeditions in Australia require great circumspection. It
is not the most rapid traveller who will get the farthest, but the
most prudent and cautious. I consider it quite possible to get
across the island, either to South Australia or to Port Essington.
Most probably it would be easier to get to the latter than the former.
From observations made on the rains and winds in Western Australia,
and careful inquiries on the same subjects when I was in South
Australia, and on a comparison of the two, I am inclined to believe
that the climates of the two colonies assimilate. A wet winter in
one is a wet winter in the other. Both receive their rains when the
wind blows from the north-west to south-west. Thus the rains from
South Australia pass from the Indian Ocean over Western Australia,
and the whole island, to South Australia. The hot wind of Western
Australia blows from the north-east; and, in fact, the hot wind of
both colonies comes from the same portion of the great island. That
which is the hot wind in summer in Western Australia is the cold wind
in winter; and the same in South Australia. The reason is obvious.
It is evident, from the fact that South Australia receives its rain
from the Indian Ocean, that there are no mountains in the interior of
sufficient elevation to intercept the clouds; that there are no
mountains in the interior, is shown also by the absence of rivers
emptying themselves into the ocean. From the observation of Mr.
Lefroy and myself, we were led to suppose that the interior consisted
for the most part of immense clay plains; the lower portion of these
plains being hollowed into the large shallow lakes we meet with in
our journey. Where the country is a little more elevated the plains
are sand instead of clay. In winter these plains are covered with
water, as the drifted leaves on the bushes testify; and the marks of
water on the surface are very evident. Now, when the winter winds
pass over these immense masses of water, the great evaporation
renders them intensely cold; and they arrive in the colony laden, (if
I may so unphilosophically express it,) with cold, caused by rapid
evaporation. In summer these very plains are equally the cause of
the hot wind; for when the rains cease, and the sun acquires his
summer power, the water is quickly evaporated, the clay becomes
baked, and the heat is reflected from the hard heated surface quite
sufficiently to raise a thermometer to 110 degrees in the shade. The
wind is now driven towards the colony laden with heat from the
cracked, baked, clay-plains in the interior; and thus it is, that at
different seasons the same country produces such opposite effects.
But although the general state of the interior is barren and
unproductive, as I imagine, I do not suppose that it is entirely so.
I believe there are many cases of good pasture land in the midst of
this sterile country; fertile spots, small when compared with the
vast area of indifferent country around them, but large in
themselves. And these pastoral oases are more cultivated than the
worthless land amid which they are placed. In these patches of good
land there are always water-holes to be found, and water-courses well
marked, conducting the surplus waters to the lakes in the clay
plains. That there are such fertile spots in the Australian deserts
is certain, for I have seen many of them myself, and they are
mentioned also by the South Australian travellers. The similarity in
most respects of vegetation in Western Australia and in South
Australia, and the identity of many plants, proves also a country of
good quality lying between the two colonies; by which such plants
were conveyed from one country to the other. Thus, the so called
white-gum is the same tree in both colonies; the mungat, or
raspberry-jam tree, is common to both; and also to the plains of New
England, in New South Wales, where (I understand) it acquires a
larger size than in Western Australia. The manch is another tree
also common to the two colonies; so is the black-wattle. The grasses
are many of them alike. But this similarity is not confined only to
the vegetable kingdom. The birds and animals are many of them also
alike. The white and the black cockatoo are common to the three
colonies, as are many kinds of the smaller parrots, the kangaroo, and
the kangaroo-rat, the numbat, the opossum, the native cat, and many
others. And this is not only true of animals of great locomotion, or
birds of long flight, as the pigeon or cockatoo, but equally so of
the opossum, the quail, and the wild-turkey. The quail and the
turkey are birds chiefly found in grassy lands, and neither fly to
any great distance: at least the quail never does; the turkey will
when much disturbed, but not otherwise. Also the water animals, as
the tortoise, are to be found in both colonies; but not the platypus,
which is confined to the country east of the great river Murrumbidgee
and its tributary the Darling.
The natives are also alike in feature and habits, evidently the same
race, with language similar in character, in both countries, with
similar weapons and methods of procuring food; having also similar
customs and laws.
Now, I infer from these facts, that the population, animal as well as
vegetable, proceeded from one country to the other; and that many
forms of vegetation in the two colonies possess no greater
difference, than the difference of soil and latitude may account for;
and that it may therefore be possible for men to find a route from
one country to the other, by carefully noting and following the lay
of the water-courses, the direction of the oases, and the nature of
the geology of the country; for that no impenetrable desert exists
between the countries, is evident from the passage of vegetables and
animals from the one to the other. What will be the benefit, some
one may ask, when such a route is discovered? Why, independent of
the knowledge gained to geography, there will be the great practical
good of opening the boundless pastures of Western Australia to the
flocks of the already overstocked lands of the other colonies. To
Western Australia the gain would be great; and to South Australia it
would be equally advantageous, as it would maintain the value of
stock there, which will rapidly fall when no more land can be found
fit for occupation. Even with all the rapid increase of population
which the great mineral abundance of that colony will continue to
create, sheep will multiply faster than the population, until they
become of the same low value as in New South Wales, where, if there
be no run sold with them, they are not worth more than the value of
the wool on their backs.
It is therefore most desirable that attempts should be made to find a
stock route from the western to the eastern coasts.
Intra-tropical Australia is more abundantly supplied with rivers, and
of a larger magnitude, than any out of the tropics, the Murray alone
excepted; and doubtless a journey across the island within the tropic
would present fewer difficulties than one direct from Perth to
Sydney, or Adelaide; but, excepting for the advancement of
geographical knowledge, there is no object to be gained by such a
journey. The best way is along the valley of the lakes, guided as
the party proceeds, by the nature of the country.
I earnestly hope that an expedition will be sent to make some effort
to penetrate the great extent of an unknown country, lying east of
Western Australia, as it is an object well worth the attention of the
Government, or of the Geographical Society.
The geology of Western Australia is not very interesting, as the
country is entirely of primary formation to the east of the Darling
range of hills: the granite every where crowning the summit of the
hills, and the immense plains consisting entirely of granitic sand,
or of hard clay containing nodules of primary rocks. This formation,
which does not in Western Australia consist of the stratified
primary series, as in South Australia, cannot be expected to yield
the abundant mineral riches that the strata of South Australia
exhibit. Probably gold may be met with, and copper and lead may be
found in the Koikunenup Range, which is not entirely a granitic
range, but is, I believe, capped with clay slate. The level country
lying between the Darling hills and the sea is of a much more recent
formation; but has not been sufficiently examined to determine its
age precisely, though I imagine it will be found to belong to the
pliocene tertiary formations. Certainly it contains many shells of
species now living in the neighbouring ocean; and the limestone ridge
running parallel with and close to the coast, and which in the colony
is falsely called magnesian limestone, contains a great proportion of
modern shells. The country lying between the hills and the sea
contains many beds of lignite; one of which, at Nornalup, on the
south coast, is more than two feet thick, and shows itself on the
face of the cliff on the north shore of the estuary. Following the
line of coast in any part of Australia, the geologist cannot fail to
be much struck by the evident marks of a gradual elevation of the
land; he will every where see the marks of the sea on the cliffs, at
a considerable height above its present level. At Cape Chatham, on
the south coast, these sea-marks are visible 300 feet above the
present level of the ocean; and can be seen on the face of the rocks,
in the hills at some distance from the coast. On my journey to
Nornalup, I discovered a lake containing shells in abundance, which
appeared to me, and were also considered by the late Dr. Hinds
(Surgeon, Royal Navy) a skilful conchologist, to be a littoral
species, common to the shores of various parts of the globe. These
shells, of no interest in themselves, become excessively interesting
as evidence of a connexion once existing between this lake and the
ocean, from which it is now at least forty miles distant. This lake
is not more than 100 feet above the present level of the ocean, and
entirely separated from any other lake or river. How, therefore,
could these marine shell-fish be living in a salt lake, unless they
had continued to exist there from the period when it was a portion of
the ocean itself? That many generations of them had lived and died
in this spot, was quite certain, from the abundance of dead shells on
the shores of this very interesting lake. Nor is the evidence of
elevation confined to the coast; all the lakes seen by Mr. Lefroy and
myself have ancient shores much higher than the present waters ever
reach. The same evidence of elevation is to be seen in the harbour
of Sydney, and in Spencer's Gulf, in South Australia. At the head of
the latter the shingle and rolled-stones clearly show that the gulf
has formerly run much farther inland: probably to Lake Torrens, the
superfluous waters of which are now discharged into the head of the
gulf. The whole plain of the Murrumbidgee has been, at not a very
distant date, beneath the ocean; as the Madrepores, and other fossils
in the limestone cliffs of the river testify. Earthquakes have been
felt in South Australia since its settlement. A very intelligent
gentleman there told me that he had noted eleven since his arrival;
quite perceptible enough to leave no doubt as to their character.
Probably the country was elevated at each shock, in a slight degree;
and perhaps before the volcano of Mount Gambier became extinct the
elevatory movements were more rapid. Be that as it may, I am quite
convinced that they are going on at this moment; and it would be well
to make marks on the cliffs in various parts of the coast, at the
present sea-level, in order to determine, after the lapse of years,
the rate of elevation.